Years ago I had a recipe (or technique) for mellowing red onions. It had to do with letting ice water and onions sit together for about a day. But that alone doesn't seem to work. I have since tried sitting onions in 1 part red wine vinegar and 1 part ice water, but don't get the same results that I remember.
contains some tips for red onions, but not necessarily addressing the red onion.
Do you have a tip/trick to mellow red onions.